Money doesn't grow on trees, but gasoline might

Researchers have made a breakthrough in the development of "green
gasoline," a liquid identical to standard gasoline yet created from
sustainable biomass sources like switchgrass and poplar trees.

Reporting in the cover article of the April 7, 2008 issue of
Chemistry & Sustainability, Energy & Materials (ChemSusChem),
chemical engineer and National Science Foundation (NSF) CAREER awardee
George Huber of the University of Massachusetts-Amherst (UMass) and his
graduate students Torren Carlson and Tushar Vispute announced the first
direct conversion of plant cellulose into gasoline components.

In the same issue, James Dumesic and colleagues from the University
of Wisconsin-Madison announce an integrated process for creating
chemical components of jet fuel using a green gasoline approach. While
Dumesic's group had previously demonstrated the production of jet-fuel
components using separate steps, their current work shows that the
steps can be integrated and run sequentially, without complex
separation and purification processes between reactors.

While it may be five to 10 years before green gasoline arrives at
the pump or finds its way into a fighter jet, these breakthroughs have
bypassed significant hurdles to bringing green gasoline biofuels to
market.

"It is likely that the future consumer will not even know that they
are putting biofuels into their car," said Huber. "Biofuels in the
future will most likely be similar in chemical composition to gasoline
and diesel fuel used today. The challenge for chemical engineers is to
efficiently produce liquid fuels from biomass while fitting into the
existing infrastructure today."

For their new approach, the UMass researchers rapidly heated
cellulose in the presence of solid catalysts, materials that speed up
reactions without sacrificing themselves in the process. They then
rapidly cooled the products to create a liquid that contains many of
the compounds found in gasoline.

The entire process was completed in under two minutes using
relatively moderate amounts of heat. The compounds that formed in that
single step, like naphthalene and toluene, make up one fourth of the
suite of chemicals found in gasoline. The liquid can be further treated
to form the remaining fuel components or can be used "as is" for a high
octane gasoline blend.

"Green gasoline is an attractive alternative to bioethanol since it
can be used in existing engines and does not incur the 30 percent gas
mileage penalty of ethanol-based flex fuel," said John Regalbuto, who
directs the Catalysis and Biocatalysis Program at NSF and supported
this research.

"In theory it requires much less energy to make than ethanol, giving
it a smaller carbon footprint and making it cheaper to produce,"
Regalbuto said. "Making it from cellulose sources such as switchgrass
or poplar trees grown as energy crops, or forest or agricultural
residues such as wood chips or corn stover, solves the lifecycle
greenhouse gas problem that has recently surfaced with corn ethanol and
soy biodiesel."

Beyond academic laboratories, both small businesses and Fortune 500
petroleum refiners are pursuing green gasoline. Companies are designing
ways to hybridize their existing refineries to enable petroleum
products including fuels, textiles, and plastics to be made from either
crude oil or biomass and the military community has shown strong
interest in making jet fuel and diesel from the same sources.

"Huber's new process for the direct conversion of cellulose to
gasoline aromatics is at the leading edge of the new ‘Green Gasoline'
alternate energy paradigm that NSF, along with other federal agencies,
is helping to promote," states Regalbuto.

Not only is the method a compact way to treat a great deal of
biomass in a short time, Regalbuto emphasized that the process, in
principle, does not require any external energy. "In fact, from the
extra heat that will be released, you can generate electricity in
addition to the biofuel," he said. "There will not be just a small
carbon footprint for the process; by recovering heat and generating
electricity, there won't be any footprint."

The latest pathways to produce green gasoline, green diesel and
green jet fuel are found in a report sponsored by NSF, the Department
of Energy and the American Chemical Society entitled "Breaking the
Chemical and Engineering Barriers to Lignocellulosic Biofuels: Next
Generation Hydrocarbon Biorefineries" released April 1
(http://www.ecs.umass.edu/biofuels/). In the report, Huber and a host
of leaders from academia, industry and government present a plan for
making green gasoline a practical solution for the impending fuel
crisis.

"We are currently working on understanding the chemistry of this
process and designing new catalysts and reactors for this single step
technique. This fundamental chemical understanding will allow us to
design more efficient processes that will accelerate the
commercialization of green gasoline," Huber said.